208 Annals of the Carnegie Museum. 



Postnodals on the front wings (7-8) d\ 7-10 (8) 9 ; on the hind 

 wings 5-7 (6) d\ 6-7 (7) 9; the numbers in parentheses the most fre- 

 quent. M 2 (= nodal sector of de Selys) arising nearest the third (75 

 percent. d\ 58 percent. 9), midway between the third and fourth 

 (8 per cent. d\ 21 per cent. 9), or nearest the fourth (16 percent. 

 cT, 21 per cent. 9) postnodal. 



The pterostigma is a most characteristic feature of this species, the 

 costal edge being shorter (100 per cent. cT9) than the proximal or 

 distal edges, and often also than the posterior edge ; the distal edge de- 

 cidedly convex and forming a much less acute angle with the anterior 

 margin of the wing than does the proximal edge. 



(All the above percentages based on 6 c?, 12 9.) 



Dimensions : Abdomen cT 16-18, 9 16-19. 5 > hind wing c? 10.5- 



11. 5, 9 11-13-5 ram - 



Habitat: — Brazil, Marajo Island, August-October, 1907, by 

 Miss Harriet Merrill, 1 9 and parts of 1 d\ 1 9. Academy of 

 Natural Sciences of Philadelphia. 



Cuyaba, ij 1 , 1 ? hom., 29 1 9 het. 30 a, 1 9 het. b ; Cachoeira 1 9 

 horn., no. 38 ; Cachoeira Cuyaba, flooded campo, January 26, 1 J* 

 and parts of 1 c?, 1 9 het. b, 1 9 het., no. 19 ; id., parts of 1 J\ 1 9 

 het. c ; Chapada, 1 9 hom. ? ; Uacaryzal, 1 9 hom. and parts of 2 9 

 hom. ; Corumba, 2 d\ 1 9 hom. ; all by H. H. Smith. Carnegie 

 Museum, Pittsburgh. 



Bolivia, Piedra Blanca, April, by H. H. Smith, 1 3 s and part of 

 1 other specimen. Carnegie Museum, Pittsburgh. 



Paraguay, Concepcion, by H. H. Smith, part of 1 d\ Carnegie 

 Museum, Pittsburgh. 



In describing this species from a single male, taken by Bates on the 

 Amazon, de Selys remarked: "Si la femelle possedait une epine 

 vulvaire, on pourrait considerer le nepos comme un Ischnura aberrant. 

 Elle a, en effet, des rapports avec ce groupe, non seulement par sa 

 petite taille et sa coloration, mais encore par la difference du ptero- 

 stigma aux quatre ailes, les appendices superieurs branchus a la base, 

 et le bout du io e segment un peu releve et bitubercule." Now that 

 the existence of a vulvar spine is known, there might be added to the 

 evidence adduced by de Selys in favor of the Ischnurine affinities of 

 this species, the apparent existence of dimorphic females. 



29 hom. := homoeochromatic. 



30 het. = heterochromatic. 



